Diabetes and spontaneous abortion: a historical review.

The recent claims that there is an increased frequency of spontaneous abortion in diabetic pregnancies prompted a reexamination of this question. More than 50 articles published in 1950 to 1986 containing relevant information provided the data for this purpose. In 8041 American and European, otherwise uninterrupted diabetic pregnancies ascertained through hospital records, mostly not specified as to the time at first examination and the interval covered, there occurred 10.0% +/- 0.3% spontaneous abortions. The frequency was significantly greater (12.7% +/- 0.7%), however, in the 1890 pregnancies observed during specifically stated extended periods. The records are marred by the lack of control pregnancies and the great absence of information regarding the variables and confounding factors that influence the spontaneous abortion rate. Nevertheless, since the results are very similar to those found in general clinical material it is most probable that there is no excess of spontaneous abortion in diabetic pregnancy. The recent claims of such an increase may have been based on the pregnant women in these studies being seen earlier and being closely examined for longer periods than has usually been the case and to the enrollment in the studies of women with unrepresentatively great risk of reproductive mishap.